/*
 * Copyright (c) 2010 Arc90 Inc
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/*
 * This code is heavily based on Arc90's readability.js (1.7.1) script
 * available at: http://code.google.com/p/arc90labs-readability
 */

/**
 * Public constructor.
 * @param {HTMLDocument} doc     The document to parse.
 * @param {Object}       options The options object.
 */
function Readability(doc, options) {
    // In some older versions, people passed a URI as the first argument. Cope:
    if (options && options.documentElement) {
        doc = options;
        options = arguments[2];
    } else if (!doc || !doc.documentElement) {
        throw new Error(
            "First argument to Readability constructor should be a document object."
        );
    }
    options = options || {};

    this._doc = doc;
    this._docJSDOMParser = this._doc.firstChild.__JSDOMParser__;
    this._articleTitle = null;
    this._articleByline = null;
    this._articleDir = null;
    this._articleSiteName = null;
    this._attempts = [];
    this._metadata = {};

    // Configurable options
    this._debug = !!options.debug;
    this._maxElemsToParse =
        options.maxElemsToParse || this.DEFAULT_MAX_ELEMS_TO_PARSE;
    this._nbTopCandidates =
        options.nbTopCandidates || this.DEFAULT_N_TOP_CANDIDATES;
    this._charThreshold = options.charThreshold || this.DEFAULT_CHAR_THRESHOLD;
    this._classesToPreserve = this.CLASSES_TO_PRESERVE.concat(
        options.classesToPreserve || []
    );
    this._keepClasses = !!options.keepClasses;
    this._serializer =
        options.serializer ||
        function (el) {
            return el.innerHTML;
        };
    this._disableJSONLD = !!options.disableJSONLD;
    this._allowedVideoRegex = options.allowedVideoRegex || this.REGEXPS.videos;
    this._linkDensityModifier = options.linkDensityModifier || 0;

    // Start with all flags set
    this._flags =
        this.FLAG_STRIP_UNLIKELYS |
        this.FLAG_WEIGHT_CLASSES |
        this.FLAG_CLEAN_CONDITIONALLY;

    // Control whether log messages are sent to the console
    if (this._debug) {
        let logNode = function (node) {
            if (node.nodeType == node.TEXT_NODE) {
                return `${node.nodeName} ("${node.textContent}")`;
            }
            let attrPairs = Array.from(node.attributes || [], function (attr) {
                return `${attr.name}="${attr.value}"`;
            }).join(" ");
            return `<${node.localName} ${attrPairs}>`;
        };
        this.log = function () {
            if (typeof console !== "undefined") {
                let args = Array.from(arguments, arg => {
                    if (arg && arg.nodeType == this.ELEMENT_NODE) {
                        return logNode(arg);
                    }
                    return arg;
                });
                args.unshift("Reader: (Readability)");
                // eslint-disable-next-line no-console
                console.log(...args);
            } else if (typeof dump !== "undefined") {
                /* global dump */
                var msg = Array.prototype.map
                    .call(arguments, function (x) {
                        return x && x.nodeName ? logNode(x) : x;
                    })
                    .join(" ");
                dump("Reader: (Readability) " + msg + "\n");
            }
        };
    } else {
        this.log = function () {};
    }
}

Readability.prototype = {
    FLAG_STRIP_UNLIKELYS: 0x1,
    FLAG_WEIGHT_CLASSES: 0x2,
    FLAG_CLEAN_CONDITIONALLY: 0x4,

    // https://developer.mozilla.org/en-US/docs/Web/API/Node/nodeType
    ELEMENT_NODE: 1,
    TEXT_NODE: 3,

    // Max number of nodes supported by this parser. Default: 0 (no limit)
    DEFAULT_MAX_ELEMS_TO_PARSE: 0,

    // The number of top candidates to consider when analysing how
    // tight the competition is among candidates.
    DEFAULT_N_TOP_CANDIDATES: 5,

    // Element tags to score by default.
    DEFAULT_TAGS_TO_SCORE: "section,h2,h3,h4,h5,h6,p,td,pre"
        .toUpperCase()
        .split(","),

    // The default number of chars an article must have in order to return a result
    DEFAULT_CHAR_THRESHOLD: 500,

    // All of the regular expressions in use within readability.
    // Defined up here so we don't instantiate them repeatedly in loops.
    REGEXPS: {
        // NOTE: These two regular expressions are duplicated in
        // Readability-readerable.js. Please keep both copies in sync.
        unlikelyCandidates:
            /-ad-|ai2html|banner|breadcrumbs|combx|comment|community|cover-wrap|disqus|extra|footer|gdpr|header|legends|menu|related|remark|replies|rss|shoutbox|sidebar|skyscraper|social|sponsor|supplemental|ad-break|agegate|pagination|pager|popup|yom-remote/i,
        okMaybeItsACandidate:
            /and|article|body|column|content|main|mathjax|shadow/i,

        positive:
            /article|body|content|entry|hentry|h-entry|main|page|pagination|post|text|blog|story/i,
        negative:
            /-ad-|hidden|^hid$| hid$| hid |^hid |banner|combx|comment|com-|contact|footer|gdpr|masthead|media|meta|outbrain|promo|related|scroll|share|shoutbox|sidebar|skyscraper|sponsor|shopping|tags|widget/i,
        extraneous:
            /print|archive|comment|discuss|e[\-]?mail|share|reply|all|login|sign|single|utility/i,
        byline: /byline|author|dateline|writtenby|p-author/i,
        replaceFonts: /<(\/?)font[^>]*>/gi,
        normalize: /\s{2,}/g,
        videos:
            /\/\/(www\.)?((dailymotion|youtube|youtube-nocookie|player\.vimeo|v\.qq|bilibili|live.bilibili)\.com|(archive|upload\.wikimedia)\.org|player\.twitch\.tv)/i,
        shareElements: /(\b|_)(share|sharedaddy)(\b|_)/i,
        nextLink: /(next|weiter|continue|>([^\|]|$)|»([^\|]|$))/i,
        prevLink: /(prev|earl|old|new|<|«)/i,
        tokenize: /\W+/g,
        whitespace: /^\s*$/,
        hasContent: /\S$/,
        hashUrl: /^#.+/,
        srcsetUrl: /(\S+)(\s+[\d.]+[xw])?(\s*(?:,|$))/g,
        b64DataUrl: /^data:\s*([^\s;,]+)\s*;\s*base64\s*,/i,
        // Commas as used in Latin, Sindhi, Chinese and various other scripts.
        // see: https://en.wikipedia.org/wiki/Comma#Comma_variants
        commas: /\u002C|\u060C|\uFE50|\uFE10|\uFE11|\u2E41|\u2E34|\u2E32|\uFF0C/g,
        // See: https://schema.org/Article
        jsonLdArticleTypes:
            /^Article|AdvertiserContentArticle|NewsArticle|AnalysisNewsArticle|AskPublicNewsArticle|BackgroundNewsArticle|OpinionNewsArticle|ReportageNewsArticle|ReviewNewsArticle|Report|SatiricalArticle|ScholarlyArticle|MedicalScholarlyArticle|SocialMediaPosting|BlogPosting|LiveBlogPosting|DiscussionForumPosting|TechArticle|APIReference$/,
        // used to see if a node's content matches words commonly used for ad blocks or loading indicators
        adWords:
            /^(ad(vertising|vertisement)?|pub(licité)?|werb(ung)?|广告|Реклама|Anuncio)$/iu,
        loadingWords:
            /^((loading|正在加载|Загрузка|chargement|cargando)(…|\.\.\.)?)$/iu,
    },

    UNLIKELY_ROLES: [
        "menu",
        "menubar",
        "complementary",
        "navigation",
        "alert",
        "alertdialog",
        "dialog",
    ],

    DIV_TO_P_ELEMS: new Set([
        "BLOCKQUOTE",
        "DL",
        "DIV",
        "IMG",
        "OL",
        "P",
        "PRE",
        "TABLE",
        "UL",
    ]),

    ALTER_TO_DIV_EXCEPTIONS: ["DIV", "ARTICLE", "SECTION", "P", "OL", "UL"],

    PRESENTATIONAL_ATTRIBUTES: [
        "align",
        "background",
        "bgcolor",
        "border",
        "cellpadding",
        "cellspacing",
        "frame",
        "hspace",
        "rules",
        "style",
        "valign",
        "vspace",
    ],

    DEPRECATED_SIZE_ATTRIBUTE_ELEMS: ["TABLE", "TH", "TD", "HR", "PRE"],

    // The commented out elements qualify as phrasing content but tend to be
    // removed by readability when put into paragraphs, so we ignore them here.
    PHRASING_ELEMS: [
        // "CANVAS", "IFRAME", "SVG", "VIDEO",
        "ABBR",
        "AUDIO",
        "B",
        "BDO",
        "BR",
        "BUTTON",
        "CITE",
        "CODE",
        "DATA",
        "DATALIST",
        "DFN",
        "EM",
        "EMBED",
        "I",
        "IMG",
        "INPUT",
        "KBD",
        "LABEL",
        "MARK",
        "MATH",
        "METER",
        "NOSCRIPT",
        "OBJECT",
        "OUTPUT",
        "PROGRESS",
        "Q",
        "RUBY",
        "SAMP",
        "SCRIPT",
        "SELECT",
        "SMALL",
        "SPAN",
        "STRONG",
        "SUB",
        "SUP",
        "TEXTAREA",
        "TIME",
        "VAR",
        "WBR",
    ],

    // These are the classes that readability sets itself.
    CLASSES_TO_PRESERVE: ["page"],

    // These are the list of HTML entities that need to be escaped.
    HTML_ESCAPE_MAP: {
        lt: "<",
        gt: ">",
        amp: "&",
        quot: '"',
        apos: "'",
    },

    /**
     * Run any post-process modifications to article content as necessary.
     *
     * @param Element
     * @return void
     **/
    _postProcessContent(articleContent) {
        // Readability cannot open relative uris so we convert them to absolute uris.
        this._fixRelativeUris(articleContent);

        this._simplifyNestedElements(articleContent);

        if (!this._keepClasses) {
            // Remove classes.
            this._cleanClasses(articleContent);
        }
    },

    /**
     * Iterates over a NodeList, calls `filterFn` for each node and removes node
     * if function returned `true`.
     *
     * If function is not passed, removes all the nodes in node list.
     *
     * @param NodeList nodeList The nodes to operate on
     * @param Function filterFn the function to use as a filter
     * @return void
     */
    _removeNodes(nodeList, filterFn) {
        // Avoid ever operating on live node lists.
        if (this._docJSDOMParser && nodeList._isLiveNodeList) {
            throw new Error("Do not pass live node lists to _removeNodes");
        }
        for (var i = nodeList.length - 1; i >= 0; i--) {
            var node = nodeList[i];
            var parentNode = node.parentNode;
            if (parentNode) {
                if (!filterFn || filterFn.call(this, node, i, nodeList)) {
                    parentNode.removeChild(node);
                }
            }
        }
    },

    /**
     * Iterates over a NodeList, and calls _setNodeTag for each node.
     *
     * @param NodeList nodeList The nodes to operate on
     * @param String newTagName the new tag name to use
     * @return void
     */
    _replaceNodeTags(nodeList, newTagName) {
        // Avoid ever operating on live node lists.
        if (this._docJSDOMParser && nodeList._isLiveNodeList) {
            throw new Error("Do not pass live node lists to _replaceNodeTags");
        }
        for (const node of nodeList) {
            this._setNodeTag(node, newTagName);
        }
    },

    /**
     * Iterate over a NodeList, which doesn't natively fully implement the Array
     * interface.
     *
     * For convenience, the current object context is applied to the provided
     * iterate function.
     *
     * @param  NodeList nodeList The NodeList.
     * @param  Function fn       The iterate function.
     * @return void
     */
    _forEachNode(nodeList, fn) {
        Array.prototype.forEach.call(nodeList, fn, this);
    },

    /**
     * Iterate over a NodeList, and return the first node that passes
     * the supplied test function
     *
     * For convenience, the current object context is applied to the provided
     * test function.
     *
     * @param  NodeList nodeList The NodeList.
     * @param  Function fn       The test function.
     * @return void
     */
    _findNode(nodeList, fn) {
        return Array.prototype.find.call(nodeList, fn, this);
    },

    /**
     * Iterate over a NodeList, return true if any of the provided iterate
     * function calls returns true, false otherwise.
     *
     * For convenience, the current object context is applied to the
     * provided iterate function.
     *
     * @param  NodeList nodeList The NodeList.
     * @param  Function fn       The iterate function.
     * @return Boolean
     */
    _someNode(nodeList, fn) {
        return Array.prototype.some.call(nodeList, fn, this);
    },

    /**
     * Iterate over a NodeList, return true if all of the provided iterate
     * function calls return true, false otherwise.
     *
     * For convenience, the current object context is applied to the
     * provided iterate function.
     *
     * @param  NodeList nodeList The NodeList.
     * @param  Function fn       The iterate function.
     * @return Boolean
     */
    _everyNode(nodeList, fn) {
        return Array.prototype.every.call(nodeList, fn, this);
    },

    _getAllNodesWithTag(node, tagNames) {
        if (node.querySelectorAll) {
            return node.querySelectorAll(tagNames.join(","));
        }
        return [].concat.apply(
            [],
            tagNames.map(function (tag) {
                var collection = node.getElementsByTagName(tag);
                return Array.isArray(collection) ? collection : Array.from(collection);
            })
        );
    },

    /**
     * Removes the class="" attribute from every element in the given
     * subtree, except those that match CLASSES_TO_PRESERVE and
     * the classesToPreserve array from the options object.
     *
     * @param Element
     * @return void
     */
    _cleanClasses(node) {
        var classesToPreserve = this._classesToPreserve;
        var className = (node.getAttribute("class") || "")
            .split(/\s+/)
            .filter(cls => classesToPreserve.includes(cls))
            .join(" ");

        if (className) {
            node.setAttribute("class", className);
        } else {
            node.removeAttribute("class");
        }

        for (node = node.firstElementChild; node; node = node.nextElementSibling) {
            this._cleanClasses(node);
        }
    },

    /**
     * Tests whether a string is a URL or not.
     *
     * @param {string} str The string to test
     * @return {boolean} true if str is a URL, false if not
     */
    _isUrl(str) {
        try {
            new URL(str);
            return true;
        } catch {
            return false;
        }
    },
    /**
     * Converts each <a> and <img> uri in the given element to an absolute URI,
     * ignoring #ref URIs.
     *
     * @param Element
     * @return void
     */
    _fixRelativeUris(articleContent) {
        var baseURI = this._doc.baseURI;
        var documentURI = this._doc.documentURI;
        function toAbsoluteURI(uri) {
            // Leave hash links alone if the base URI matches the document URI:
            if (baseURI == documentURI && uri.charAt(0) == "#") {
                return uri;
            }

            // Otherwise, resolve against base URI:
            try {
                return new URL(uri, baseURI).href;
            } catch (ex) {
                // Something went wrong, just return the original:
            }
            return uri;
        }

        var links = this._getAllNodesWithTag(articleContent, ["a"]);
        this._forEachNode(links, function (link) {
            var href = link.getAttribute("href");
            if (href) {
                // Remove links with javascript: URIs, since
                // they won't work after scripts have been removed from the page.
                if (href.indexOf("javascript:") === 0) {
                    // if the link only contains simple text content, it can be converted to a text node
                    if (
                        link.childNodes.length === 1 &&
                        link.childNodes[0].nodeType === this.TEXT_NODE
                    ) {
                        var text = this._doc.createTextNode(link.textContent);
                        link.parentNode.replaceChild(text, link);
                    } else {
                        // if the link has multiple children, they should all be preserved
                        var container = this._doc.createElement("span");
                        while (link.firstChild) {
                            container.appendChild(link.firstChild);
                        }
                        link.parentNode.replaceChild(container, link);
                    }
                } else {
                    link.setAttribute("href", toAbsoluteURI(href));
                }
            }
        });

        var mediums = this._getAllNodesWithTag(articleContent, [
            "img",
            "picture",
            "figure",
            "video",
            "audio",
            "source",
        ]);

        this._forEachNode(mediums, function (media) {
            var src = media.getAttribute("src");
            var poster = media.getAttribute("poster");
            var srcset = media.getAttribute("srcset");

            if (src) {
                media.setAttribute("src", toAbsoluteURI(src));
            }

            if (poster) {
                media.setAttribute("poster", toAbsoluteURI(poster));
            }

            if (srcset) {
                var newSrcset = srcset.replace(
                    this.REGEXPS.srcsetUrl,
                    function (_, p1, p2, p3) {
                        return toAbsoluteURI(p1) + (p2 || "") + p3;
                    }
                );

                media.setAttribute("srcset", newSrcset);
            }
        });
    },

    _simplifyNestedElements(articleContent) {
        var node = articleContent;

        while (node) {
            if (
                node.parentNode &&
                ["DIV", "SECTION"].includes(node.tagName) &&
                !(node.id && node.id.startsWith("readability"))
            ) {
                if (this._isElementWithoutContent(node)) {
                    node = this._removeAndGetNext(node);
                    continue;
                } else if (
                    this._hasSingleTagInsideElement(node, "DIV") ||
                    this._hasSingleTagInsideElement(node, "SECTION")
                ) {
                    var child = node.children[0];
                    for (var i = 0; i < node.attributes.length; i++) {
                        child.setAttributeNode(node.attributes[i].cloneNode());
                    }
                    node.parentNode.replaceChild(child, node);
                    node = child;
                    continue;
                }
            }

            node = this._getNextNode(node);
        }
    },

    /**
     * Get the article title as an H1.
     *
     * @return string
     **/
    _getArticleTitle() {
        var doc = this._doc;
        var curTitle = "";
        var origTitle = "";

        try {
            curTitle = origTitle = doc.title.trim();

            // If they had an element with id "title" in their HTML
            if (typeof curTitle !== "string") {
                curTitle = origTitle = this._getInnerText(
                    doc.getElementsByTagName("title")[0]
                );
            }
        } catch (e) {
            /* ignore exceptions setting the title. */
        }

        var titleHadHierarchicalSeparators = false;
        function wordCount(str) {
            return str.split(/\s+/).length;
        }

        // If there's a separator in the title, first remove the final part
        const titleSeparators = /\|\-–—\\\/>»/.source;
        if (new RegExp(`\\s[${titleSeparators}]\\s`).test(curTitle)) {
            titleHadHierarchicalSeparators = /\s[\\\/>»]\s/.test(curTitle);
            let allSeparators = Array.from(
                origTitle.matchAll(new RegExp(`\\s[${titleSeparators}]\\s`, "gi"))
            );
            curTitle = origTitle.substring(0, allSeparators.pop().index);

            // If the resulting title is too short, remove the first part instead:
            if (wordCount(curTitle) < 3) {
                curTitle = origTitle.replace(
                    new RegExp(`^[^${titleSeparators}]*[${titleSeparators}]`, "gi"),
                    ""
                );
            }
        } else if (curTitle.includes(": ")) {
            // Check if we have an heading containing this exact string, so we
            // could assume it's the full title.
            var headings = this._getAllNodesWithTag(doc, ["h1", "h2"]);
            var trimmedTitle = curTitle.trim();
            var match = this._someNode(headings, function (heading) {
                return heading.textContent.trim() === trimmedTitle;
            });

            // If we don't, let's extract the title out of the original title string.
            if (!match) {
                curTitle = origTitle.substring(origTitle.lastIndexOf(":") + 1);

                // If the title is now too short, try the first colon instead:
                if (wordCount(curTitle) < 3) {
                    curTitle = origTitle.substring(origTitle.indexOf(":") + 1);
                    // But if we have too many words before the colon there's something weird
                    // with the titles and the H tags so let's just use the original title instead
                } else if (wordCount(origTitle.substr(0, origTitle.indexOf(":"))) > 5) {
                    curTitle = origTitle;
                }
            }
        } else if (curTitle.length > 150 || curTitle.length < 15) {
            var hOnes = doc.getElementsByTagName("h1");

            if (hOnes.length === 1) {
                curTitle = this._getInnerText(hOnes[0]);
            }
        }

        curTitle = curTitle.trim().replace(this.REGEXPS.normalize, " ");
        // If we now have 4 words or fewer as our title, and either no
        // 'hierarchical' separators (\, /, > or ») were found in the original
        // title or we decreased the number of words by more than 1 word, use
        // the original title.
        var curTitleWordCount = wordCount(curTitle);
        if (
            curTitleWordCount <= 4 &&
            (!titleHadHierarchicalSeparators ||
                curTitleWordCount !=
                wordCount(
                    origTitle.replace(new RegExp(`\\s[${titleSeparators}]\\s`, "g"), "")
                ) -
                1)
        ) {
            curTitle = origTitle;
        }

        return curTitle;
    },

    /**
     * Prepare the HTML document for readability to scrape it.
     * This includes things like stripping javascript, CSS, and handling terrible markup.
     *
     * @return void
     **/
    _prepDocument() {
        var doc = this._doc;

        // Remove all style tags in head
        this._removeNodes(this._getAllNodesWithTag(doc, ["style"]));

        if (doc.body) {
            this._replaceBrs(doc.body);
        }

        this._replaceNodeTags(this._getAllNodesWithTag(doc, ["font"]), "SPAN");
    },

    /**
     * Finds the next node, starting from the given node, and ignoring
     * whitespace in between. If the given node is an element, the same node is
     * returned.
     */
    _nextNode(node) {
        var next = node;
        while (
            next &&
            next.nodeType != this.ELEMENT_NODE &&
            this.REGEXPS.whitespace.test(next.textContent)
            ) {
            next = next.nextSibling;
        }
        return next;
    },

    /**
     * Replaces 2 or more successive <br> elements with a single <p>.
     * Whitespace between <br> elements are ignored. For example:
     *   <div>foo<br>bar<br> <br><br>abc</div>
     * will become:
     *   <div>foo<br>bar<p>abc</p></div>
     */
    _replaceBrs(elem) {
        this._forEachNode(this._getAllNodesWithTag(elem, ["br"]), function (br) {
            var next = br.nextSibling;

            // Whether 2 or more <br> elements have been found and replaced with a
            // <p> block.
            var replaced = false;

            // If we find a <br> chain, remove the <br>s until we hit another node
            // or non-whitespace. This leaves behind the first <br> in the chain
            // (which will be replaced with a <p> later).
            while ((next = this._nextNode(next)) && next.tagName == "BR") {
                replaced = true;
                var brSibling = next.nextSibling;
                next.remove();
                next = brSibling;
            }

            // If we removed a <br> chain, replace the remaining <br> with a <p>. Add
            // all sibling nodes as children of the <p> until we hit another <br>
            // chain.
            if (replaced) {
                var p = this._doc.createElement("p");
                br.parentNode.replaceChild(p, br);

                next = p.nextSibling;
                while (next) {
                    // If we've hit another <br><br>, we're done adding children to this <p>.
                    if (next.tagName == "BR") {
                        var nextElem = this._nextNode(next.nextSibling);
                        if (nextElem && nextElem.tagName == "BR") {
                            break;
                        }
                    }

                    if (!this._isPhrasingContent(next)) {
                        break;
                    }

                    // Otherwise, make this node a child of the new <p>.
                    var sibling = next.nextSibling;
                    p.appendChild(next);
                    next = sibling;
                }

                while (p.lastChild && this._isWhitespace(p.lastChild)) {
                    p.lastChild.remove();
                }

                if (p.parentNode.tagName === "P") {
                    this._setNodeTag(p.parentNode, "DIV");
                }
            }
        });
    },

    _setNodeTag(node, tag) {
        this.log("_setNodeTag", node, tag);
        if (this._docJSDOMParser) {
            node.localName = tag.toLowerCase();
            node.tagName = tag.toUpperCase();
            return node;
        }

        var replacement = node.ownerDocument.createElement(tag);
        while (node.firstChild) {
            replacement.appendChild(node.firstChild);
        }
        node.parentNode.replaceChild(replacement, node);
        if (node.readability) {
            replacement.readability = node.readability;
        }

        for (var i = 0; i < node.attributes.length; i++) {
            replacement.setAttributeNode(node.attributes[i].cloneNode());
        }
        return replacement;
    },

    /**
     * Prepare the article node for display. Clean out any inline styles,
     * iframes, forms, strip extraneous <p> tags, etc.
     *
     * @param Element
     * @return void
     **/
    _prepArticle(articleContent) {
        this._cleanStyles(articleContent);

        // Check for data tables before we continue, to avoid removing items in
        // those tables, which will often be isolated even though they're
        // visually linked to other content-ful elements (text, images, etc.).
        this._markDataTables(articleContent);

        this._fixLazyImages(articleContent);

        // Clean out junk from the article content
        this._cleanConditionally(articleContent, "form");
        this._cleanConditionally(articleContent, "fieldset");
        this._clean(articleContent, "object");
        this._clean(articleContent, "embed");
        this._clean(articleContent, "footer");
        this._clean(articleContent, "link");
        this._clean(articleContent, "aside");

        // Clean out elements with little content that have "share" in their id/class combinations from final top candidates,
        // which means we don't remove the top candidates even they have "share".

        var shareElementThreshold = this.DEFAULT_CHAR_THRESHOLD;

        this._forEachNode(articleContent.children, function (topCandidate) {
            this._cleanMatchedNodes(topCandidate, function (node, matchString) {
                return (
                    this.REGEXPS.shareElements.test(matchString) &&
                    node.textContent.length < shareElementThreshold
                );
            });
        });

        this._clean(articleContent, "iframe");
        this._clean(articleContent, "input");
        this._clean(articleContent, "textarea");
        this._clean(articleContent, "select");
        this._clean(articleContent, "button");
        this._cleanHeaders(articleContent);

        // Do these last as the previous stuff may have removed junk
        // that will affect these
        this._cleanConditionally(articleContent, "table");
        this._cleanConditionally(articleContent, "ul");
        this._cleanConditionally(articleContent, "div");

        // replace H1 with H2 as H1 should be only title that is displayed separately
        this._replaceNodeTags(
            this._getAllNodesWithTag(articleContent, ["h1"]),
            "h2"
        );

        // Remove extra paragraphs
        this._removeNodes(
            this._getAllNodesWithTag(articleContent, ["p"]),
            function (paragraph) {
                // At this point, nasty iframes have been removed; only embedded video
                // ones remain.
                var contentElementCount = this._getAllNodesWithTag(paragraph, [
                    "img",
                    "embed",
                    "object",
                    "iframe",
                ]).length;
                return (
                    contentElementCount === 0 && !this._getInnerText(paragraph, false)
                );
            }
        );

        this._forEachNode(
            this._getAllNodesWithTag(articleContent, ["br"]),
            function (br) {
                var next = this._nextNode(br.nextSibling);
                if (next && next.tagName == "P") {
                    br.remove();
                }
            }
        );

        // Remove single-cell tables
        this._forEachNode(
            this._getAllNodesWithTag(articleContent, ["table"]),
            function (table) {
                var tbody = this._hasSingleTagInsideElement(table, "TBODY")
                    ? table.firstElementChild
                    : table;
                if (this._hasSingleTagInsideElement(tbody, "TR")) {
                    var row = tbody.firstElementChild;
                    if (this._hasSingleTagInsideElement(row, "TD")) {
                        var cell = row.firstElementChild;
                        cell = this._setNodeTag(
                            cell,
                            this._everyNode(cell.childNodes, this._isPhrasingContent)
                                ? "P"
                                : "DIV"
                        );
                        table.parentNode.replaceChild(cell, table);
                    }
                }
            }
        );
    },

    /**
     * Initialize a node with the readability object. Also checks the
     * className/id for special names to add to its score.
     *
     * @param Element
     * @return void
     **/
    _initializeNode(node) {
        node.readability = { contentScore: 0 };

        switch (node.tagName) {
            case "DIV":
                node.readability.contentScore += 5;
                break;

            case "PRE":
            case "TD":
            case "BLOCKQUOTE":
                node.readability.contentScore += 3;
                break;

            case "ADDRESS":
            case "OL":
            case "UL":
            case "DL":
            case "DD":
            case "DT":
            case "LI":
            case "FORM":
                node.readability.contentScore -= 3;
                break;

            case "H1":
            case "H2":
            case "H3":
            case "H4":
            case "H5":
            case "H6":
            case "TH":
                node.readability.contentScore -= 5;
                break;
        }

        node.readability.contentScore += this._getClassWeight(node);
    },

    _removeAndGetNext(node) {
        var nextNode = this._getNextNode(node, true);
        node.remove();
        return nextNode;
    },

    /**
     * Traverse the DOM from node to node, starting at the node passed in.
     * Pass true for the second parameter to indicate this node itself
     * (and its kids) are going away, and we want the next node over.
     *
     * Calling this in a loop will traverse the DOM depth-first.
     *
     * @param {Element} node
     * @param {boolean} ignoreSelfAndKids
     * @return {Element}
     */
    _getNextNode(node, ignoreSelfAndKids) {
        // First check for kids if those aren't being ignored
        if (!ignoreSelfAndKids && node.firstElementChild) {
            return node.firstElementChild;
        }
        // Then for siblings...
        if (node.nextElementSibling) {
            return node.nextElementSibling;
        }
        // And finally, move up the parent chain *and* find a sibling
        // (because this is depth-first traversal, we will have already
        // seen the parent nodes themselves).
        do {
            node = node.parentNode;
        } while (node && !node.nextElementSibling);
        return node && node.nextElementSibling;
    },

    // compares second text to first one
    // 1 = same text, 0 = completely different text
    // works the way that it splits both texts into words and then finds words that are unique in second text
    // the result is given by the lower length of unique parts
    _textSimilarity(textA, textB) {
        var tokensA = textA
            .toLowerCase()
            .split(this.REGEXPS.tokenize)
            .filter(Boolean);
        var tokensB = textB
            .toLowerCase()
            .split(this.REGEXPS.tokenize)
            .filter(Boolean);
        if (!tokensA.length || !tokensB.length) {
            return 0;
        }
        var uniqTokensB = tokensB.filter(token => !tokensA.includes(token));
        var distanceB = uniqTokensB.join(" ").length / tokensB.join(" ").length;
        return 1 - distanceB;
    },

    /**
     * Checks whether an element node contains a valid byline
     *
     * @param node {Element}
     * @param matchString {string}
     * @return boolean
     */
    _isValidByline(node, matchString) {
        var rel = node.getAttribute("rel");
        var itemprop = node.getAttribute("itemprop");
        var bylineLength = node.textContent.trim().length;

        return (
            (rel === "author" ||
                (itemprop && itemprop.includes("author")) ||
                this.REGEXPS.byline.test(matchString)) &&
            !!bylineLength &&
            bylineLength < 100
        );
    },

    _getNodeAncestors(node, maxDepth) {
        maxDepth = maxDepth || 0;
        var i = 0,
            ancestors = [];
        while (node.parentNode) {
            ancestors.push(node.parentNode);
            if (maxDepth && ++i === maxDepth) {
                break;
            }
            node = node.parentNode;
        }
        return ancestors;
    },

    /***
     * grabArticle - Using a variety of metrics (content score, classname, element types), find the content that is
     *         most likely to be the stuff a user wants to read. Then return it wrapped up in a div.
     *
     * @param page a document to run upon. Needs to be a full document, complete with body.
     * @return Element
     **/
    /* eslint-disable-next-line complexity */
    _grabArticle(page) {
        this.log("**** grabArticle ****");
        var doc = this._doc;
        var isPaging = page !== null;
        page = page ? page : this._doc.body;

        // We can't grab an article if we don't have a page!
        if (!page) {
            this.log("No body found in document. Abort.");
            return null;
        }

        var pageCacheHtml = page.innerHTML;

        while (true) {
            this.log("Starting grabArticle loop");
            var stripUnlikelyCandidates = this._flagIsActive(
                this.FLAG_STRIP_UNLIKELYS
            );

            // First, node prepping. Trash nodes that look cruddy (like ones with the
            // class name "comment", etc), and turn divs into P tags where they have been
            // used inappropriately (as in, where they contain no other block level elements.)
            var elementsToScore = [];
            var node = this._doc.documentElement;

            let shouldRemoveTitleHeader = true;

            while (node) {
                if (node.tagName === "HTML") {
                    this._articleLang = node.getAttribute("lang");
                }

                var matchString = node.className + " " + node.id;

                if (!this._isProbablyVisible(node)) {
                    this.log("Removing hidden node - " + matchString);
                    node = this._removeAndGetNext(node);
                    continue;
                }

                // User is not able to see elements applied with both "aria-modal = true" and "role = dialog"
                if (
                    node.getAttribute("aria-modal") == "true" &&
                    node.getAttribute("role") == "dialog"
                ) {
                    node = this._removeAndGetNext(node);
                    continue;
                }

                // If we don't have a byline yet check to see if this node is a byline; if it is store the byline and remove the node.
                if (
                    !this._articleByline &&
                    !this._metadata.byline &&
                    this._isValidByline(node, matchString)
                ) {
                    // Find child node matching [itemprop="name"] and use that if it exists for a more accurate author name byline
                    var endOfSearchMarkerNode = this._getNextNode(node, true);
                    var next = this._getNextNode(node);
                    var itemPropNameNode = null;
                    while (next && next != endOfSearchMarkerNode) {
                        var itemprop = next.getAttribute("itemprop");
                        if (itemprop && itemprop.includes("name")) {
                            itemPropNameNode = next;
                            break;
                        } else {
                            next = this._getNextNode(next);
                        }
                    }
                    this._articleByline = (itemPropNameNode ?? node).textContent.trim();
                    node = this._removeAndGetNext(node);
                    continue;
                }

                if (shouldRemoveTitleHeader && this._headerDuplicatesTitle(node)) {
                    this.log(
                        "Removing header: ",
                        node.textContent.trim(),
                        this._articleTitle.trim()
                    );
                    shouldRemoveTitleHeader = false;
                    node = this._removeAndGetNext(node);
                    continue;
                }

                // Remove unlikely candidates
                if (stripUnlikelyCandidates) {
                    if (
                        this.REGEXPS.unlikelyCandidates.test(matchString) &&
                        !this.REGEXPS.okMaybeItsACandidate.test(matchString) &&
                        !this._hasAncestorTag(node, "table") &&
                        !this._hasAncestorTag(node, "code") &&
                        node.tagName !== "BODY" &&
                        node.tagName !== "A"
                    ) {
                        this.log("Removing unlikely candidate - " + matchString);
                        node = this._removeAndGetNext(node);
                        continue;
                    }

                    if (this.UNLIKELY_ROLES.includes(node.getAttribute("role"))) {
                        this.log(
                            "Removing content with role " +
                            node.getAttribute("role") +
                            " - " +
                            matchString
                        );
                        node = this._removeAndGetNext(node);
                        continue;
                    }
                }

                // Remove DIV, SECTION, and HEADER nodes without any content(e.g. text, image, video, or iframe).
                if (
                    (node.tagName === "DIV" ||
                        node.tagName === "SECTION" ||
                        node.tagName === "HEADER" ||
                        node.tagName === "H1" ||
                        node.tagName === "H2" ||
                        node.tagName === "H3" ||
                        node.tagName === "H4" ||
                        node.tagName === "H5" ||
                        node.tagName === "H6") &&
                    this._isElementWithoutContent(node)
                ) {
                    node = this._removeAndGetNext(node);
                    continue;
                }

                if (this.DEFAULT_TAGS_TO_SCORE.includes(node.tagName)) {
                    elementsToScore.push(node);
                }

                // Turn all divs that don't have children block level elements into p's
                if (node.tagName === "DIV") {
                    // Put phrasing content into paragraphs.
                    var p = null;
                    var childNode = node.firstChild;
                    while (childNode) {
                        var nextSibling = childNode.nextSibling;
                        if (this._isPhrasingContent(childNode)) {
                            if (p !== null) {
                                p.appendChild(childNode);
                            } else if (!this._isWhitespace(childNode)) {
                                p = doc.createElement("p");
                                node.replaceChild(p, childNode);
                                p.appendChild(childNode);
                            }
                        } else if (p !== null) {
                            while (p.lastChild && this._isWhitespace(p.lastChild)) {
                                p.lastChild.remove();
                            }
                            p = null;
                        }
                        childNode = nextSibling;
                    }

                    // Sites like http://mobile.slate.com encloses each paragraph with a DIV
                    // element. DIVs with only a P element inside and no text content can be
                    // safely converted into plain P elements to avoid confusing the scoring
                    // algorithm with DIVs with are, in practice, paragraphs.
                    if (
                        this._hasSingleTagInsideElement(node, "P") &&
                        this._getLinkDensity(node) < 0.25
                    ) {
                        var newNode = node.children[0];
                        node.parentNode.replaceChild(newNode, node);
                        node = newNode;
                        elementsToScore.push(node);
                    } else if (!this._hasChildBlockElement(node)) {
                        node = this._setNodeTag(node, "P");
                        elementsToScore.push(node);
                    }
                }
                node = this._getNextNode(node);
            }

            /**
             * Loop through all paragraphs, and assign a score to them based on how content-y they look.
             * Then add their score to their parent node.
             *
             * A score is determined by things like number of commas, class names, etc. Maybe eventually link density.
             **/
            var candidates = [];
            this._forEachNode(elementsToScore, function (elementToScore) {
                if (
                    !elementToScore.parentNode ||
                    typeof elementToScore.parentNode.tagName === "undefined"
                ) {
                    return;
                }

                // If this paragraph is less than 25 characters, don't even count it.
                var innerText = this._getInnerText(elementToScore);
                if (innerText.length < 25) {
                    return;
                }

                // Exclude nodes with no ancestor.
                var ancestors = this._getNodeAncestors(elementToScore, 5);
                if (ancestors.length === 0) {
                    return;
                }

                var contentScore = 0;

                // Add a point for the paragraph itself as a base.
                contentScore += 1;

                // Add points for any commas within this paragraph.
                contentScore += innerText.split(this.REGEXPS.commas).length;

                // For every 100 characters in this paragraph, add another point. Up to 3 points.
                contentScore += Math.min(Math.floor(innerText.length / 100), 3);

                // Initialize and score ancestors.
                this._forEachNode(ancestors, function (ancestor, level) {
                    if (
                        !ancestor.tagName ||
                        !ancestor.parentNode ||
                        typeof ancestor.parentNode.tagName === "undefined"
                    ) {
                        return;
                    }

                    if (typeof ancestor.readability === "undefined") {
                        this._initializeNode(ancestor);
                        candidates.push(ancestor);
                    }

                    // Node score divider:
                    // - parent:             1 (no division)
                    // - grandparent:        2
                    // - great grandparent+: ancestor level * 3
                    if (level === 0) {
                        var scoreDivider = 1;
                    } else if (level === 1) {
                        scoreDivider = 2;
                    } else {
                        scoreDivider = level * 3;
                    }
                    ancestor.readability.contentScore += contentScore / scoreDivider;
                });
            });

            // After we've calculated scores, loop through all of the possible
            // candidate nodes we found and find the one with the highest score.
            var topCandidates = [];
            for (var c = 0, cl = candidates.length; c < cl; c += 1) {
                var candidate = candidates[c];

                // Scale the final candidates score based on link density. Good content
                // should have a relatively small link density (5% or less) and be mostly
                // unaffected by this operation.
                var candidateScore =
                    candidate.readability.contentScore *
                    (1 - this._getLinkDensity(candidate));
                candidate.readability.contentScore = candidateScore;

                this.log("Candidate:", candidate, "with score " + candidateScore);

                for (var t = 0; t < this._nbTopCandidates; t++) {
                    var aTopCandidate = topCandidates[t];

                    if (
                        !aTopCandidate ||
                        candidateScore > aTopCandidate.readability.contentScore
                    ) {
                        topCandidates.splice(t, 0, candidate);
                        if (topCandidates.length > this._nbTopCandidates) {
                            topCandidates.pop();
                        }
                        break;
                    }
                }
            }

            var topCandidate = topCandidates[0] || null;
            var neededToCreateTopCandidate = false;
            var parentOfTopCandidate;

            // If we still have no top candidate, just use the body as a last resort.
            // We also have to copy the body node so it is something we can modify.
            if (topCandidate === null || topCandidate.tagName === "BODY") {
                // Move all of the page's children into topCandidate
                topCandidate = doc.createElement("DIV");
                neededToCreateTopCandidate = true;
                // Move everything (not just elements, also text nodes etc.) into the container
                // so we even include text directly in the body:
                while (page.firstChild) {
                    this.log("Moving child out:", page.firstChild);
                    topCandidate.appendChild(page.firstChild);
                }

                page.appendChild(topCandidate);

                this._initializeNode(topCandidate);
            } else if (topCandidate) {
                // Find a better top candidate node if it contains (at least three) nodes which belong to `topCandidates` array
                // and whose scores are quite closed with current `topCandidate` node.
                var alternativeCandidateAncestors = [];
                for (var i = 1; i < topCandidates.length; i++) {
                    if (
                        topCandidates[i].readability.contentScore /
                        topCandidate.readability.contentScore >=
                        0.75
                    ) {
                        alternativeCandidateAncestors.push(
                            this._getNodeAncestors(topCandidates[i])
                        );
                    }
                }
                var MINIMUM_TOPCANDIDATES = 3;
                if (alternativeCandidateAncestors.length >= MINIMUM_TOPCANDIDATES) {
                    parentOfTopCandidate = topCandidate.parentNode;
                    while (parentOfTopCandidate.tagName !== "BODY") {
                        var listsContainingThisAncestor = 0;
                        for (
                            var ancestorIndex = 0;
                            ancestorIndex < alternativeCandidateAncestors.length &&
                            listsContainingThisAncestor < MINIMUM_TOPCANDIDATES;
                            ancestorIndex++
                        ) {
                            listsContainingThisAncestor += Number(
                                alternativeCandidateAncestors[ancestorIndex].includes(
                                    parentOfTopCandidate
                                )
                            );
                        }
                        if (listsContainingThisAncestor >= MINIMUM_TOPCANDIDATES) {
                            topCandidate = parentOfTopCandidate;
                            break;
                        }
                        parentOfTopCandidate = parentOfTopCandidate.parentNode;
                    }
                }
                if (!topCandidate.readability) {
                    this._initializeNode(topCandidate);
                }

                // Because of our bonus system, parents of candidates might have scores
                // themselves. They get half of the node. There won't be nodes with higher
                // scores than our topCandidate, but if we see the score going *up* in the first
                // few steps up the tree, that's a decent sign that there might be more content
                // lurking in other places that we want to unify in. The sibling stuff
                // below does some of that - but only if we've looked high enough up the DOM
                // tree.
                parentOfTopCandidate = topCandidate.parentNode;
                var lastScore = topCandidate.readability.contentScore;
                // The scores shouldn't get too low.
                var scoreThreshold = lastScore / 3;
                while (parentOfTopCandidate.tagName !== "BODY") {
                    if (!parentOfTopCandidate.readability) {
                        parentOfTopCandidate = parentOfTopCandidate.parentNode;
                        continue;
                    }
                    var parentScore = parentOfTopCandidate.readability.contentScore;
                    if (parentScore < scoreThreshold) {
                        break;
                    }
                    if (parentScore > lastScore) {
                        // Alright! We found a better parent to use.
                        topCandidate = parentOfTopCandidate;
                        break;
                    }
                    lastScore = parentOfTopCandidate.readability.contentScore;
                    parentOfTopCandidate = parentOfTopCandidate.parentNode;
                }

                // If the top candidate is the only child, use parent instead. This will help sibling
                // joining logic when adjacent content is actually located in parent's sibling node.
                parentOfTopCandidate = topCandidate.parentNode;
                while (
                    parentOfTopCandidate.tagName != "BODY" &&
                    parentOfTopCandidate.children.length == 1
                    ) {
                    topCandidate = parentOfTopCandidate;
                    parentOfTopCandidate = topCandidate.parentNode;
                }
                if (!topCandidate.readability) {
                    this._initializeNode(topCandidate);
                }
            }

            // Now that we have the top candidate, look through its siblings for content
            // that might also be related. Things like preambles, content split by ads
            // that we removed, etc.
            var articleContent = doc.createElement("DIV");
            if (isPaging) {
                articleContent.id = "readability-content";
            }

            var siblingScoreThreshold = Math.max(
                10,
                topCandidate.readability.contentScore * 0.2
            );
            // Keep potential top candidate's parent node to try to get text direction of it later.
            parentOfTopCandidate = topCandidate.parentNode;
            var siblings = parentOfTopCandidate.children;

            for (var s = 0, sl = siblings.length; s < sl; s++) {
                var sibling = siblings[s];
                var append = false;

                this.log(
                    "Looking at sibling node:",
                    sibling,
                    sibling.readability
                        ? "with score " + sibling.readability.contentScore
                        : ""
                );
                this.log(
                    "Sibling has score",
                    sibling.readability ? sibling.readability.contentScore : "Unknown"
                );

                if (sibling === topCandidate) {
                    append = true;
                } else {
                    var contentBonus = 0;

                    // Give a bonus if sibling nodes and top candidates have the example same classname
                    if (
                        sibling.className === topCandidate.className &&
                        topCandidate.className !== ""
                    ) {
                        contentBonus += topCandidate.readability.contentScore * 0.2;
                    }

                    if (
                        sibling.readability &&
                        sibling.readability.contentScore + contentBonus >=
                        siblingScoreThreshold
                    ) {
                        append = true;
                    } else if (sibling.nodeName === "P") {
                        var linkDensity = this._getLinkDensity(sibling);
                        var nodeContent = this._getInnerText(sibling);
                        var nodeLength = nodeContent.length;

                        if (nodeLength > 80 && linkDensity < 0.25) {
                            append = true;
                        } else if (
                            nodeLength < 80 &&
                            nodeLength > 0 &&
                            linkDensity === 0 &&
                            nodeContent.search(/\.( |$)/) !== -1
                        ) {
                            append = true;
                        }
                    }
                }

                if (append) {
                    this.log("Appending node:", sibling);

                    if (!this.ALTER_TO_DIV_EXCEPTIONS.includes(sibling.nodeName)) {
                        // We have a node that isn't a common block level element, like a form or td tag.
                        // Turn it into a div so it doesn't get filtered out later by accident.
                        this.log("Altering sibling:", sibling, "to div.");

                        sibling = this._setNodeTag(sibling, "DIV");
                    }

                    articleContent.appendChild(sibling);
                    // Fetch children again to make it compatible
                    // with DOM parsers without live collection support.
                    siblings = parentOfTopCandidate.children;
                    // siblings is a reference to the children array, and
                    // sibling is removed from the array when we call appendChild().
                    // As a result, we must revisit this index since the nodes
                    // have been shifted.
                    s -= 1;
                    sl -= 1;
                }
            }

            if (this._debug) {
                this.log("Article content pre-prep: " + articleContent.innerHTML);
            }
            // So we have all of the content that we need. Now we clean it up for presentation.
            this._prepArticle(articleContent);
            if (this._debug) {
                this.log("Article content post-prep: " + articleContent.innerHTML);
            }

            if (neededToCreateTopCandidate) {
                // We already created a fake div thing, and there wouldn't have been any siblings left
                // for the previous loop, so there's no point trying to create a new div, and then
                // move all the children over. Just assign IDs and class names here. No need to append
                // because that already happened anyway.
                topCandidate.id = "readability-page-1";
                topCandidate.className = "page";
            } else {
                var div = doc.createElement("DIV");
                div.id = "readability-page-1";
                div.className = "page";
                while (articleContent.firstChild) {
                    div.appendChild(articleContent.firstChild);
                }
                articleContent.appendChild(div);
            }

            if (this._debug) {
                this.log("Article content after paging: " + articleContent.innerHTML);
            }

            var parseSuccessful = true;

            // Now that we've gone through the full algorithm, check to see if
            // we got any meaningful content. If we didn't, we may need to re-run
            // grabArticle with different flags set. This gives us a higher likelihood of
            // finding the content, and the sieve approach gives us a higher likelihood of
            // finding the -right- content.
            var textLength = this._getInnerText(articleContent, true).length;
            if (textLength < this._charThreshold) {
                parseSuccessful = false;
                // eslint-disable-next-line no-unsanitized/property
                page.innerHTML = pageCacheHtml;

                this._attempts.push({
                    articleContent,
                    textLength,
                });

                if (this._flagIsActive(this.FLAG_STRIP_UNLIKELYS)) {
                    this._removeFlag(this.FLAG_STRIP_UNLIKELYS);
                } else if (this._flagIsActive(this.FLAG_WEIGHT_CLASSES)) {
                    this._removeFlag(this.FLAG_WEIGHT_CLASSES);
                } else if (this._flagIsActive(this.FLAG_CLEAN_CONDITIONALLY)) {
                    this._removeFlag(this.FLAG_CLEAN_CONDITIONALLY);
                } else {
                    // No luck after removing flags, just return the longest text we found during the different loops
                    this._attempts.sort(function (a, b) {
                        return b.textLength - a.textLength;
                    });

                    // But first check if we actually have something
                    if (!this._attempts[0].textLength) {
                        return null;
                    }

                    articleContent = this._attempts[0].articleContent;
                    parseSuccessful = true;
                }
            }

            if (parseSuccessful) {
                // Find out text direction from ancestors of final top candidate.
                var ancestors = [parentOfTopCandidate, topCandidate].concat(
                    this._getNodeAncestors(parentOfTopCandidate)
                );
                this._someNode(ancestors, function (ancestor) {
                    if (!ancestor.tagName) {
                        return false;
                    }
                    var articleDir = ancestor.getAttribute("dir");
                    if (articleDir) {
                        this._articleDir = articleDir;
                        return true;
                    }
                    return false;
                });
                return articleContent;
            }
        }
    },

    /**
     * Converts some of the common HTML entities in string to their corresponding characters.
     *
     * @param str {string} - a string to unescape.
     * @return string without HTML entity.
     */
    _unescapeHtmlEntities(str) {
        if (!str) {
            return str;
        }

        var htmlEscapeMap = this.HTML_ESCAPE_MAP;
        return str
            .replace(/&(quot|amp|apos|lt|gt);/g, function (_, tag) {
                return htmlEscapeMap[tag];
            })
            .replace(/&#(?:x([0-9a-f]+)|([0-9]+));/gi, function (_, hex, numStr) {
                var num = parseInt(hex || numStr, hex ? 16 : 10);

                // these character references are replaced by a conforming HTML parser
                if (num == 0 || num > 0x10ffff || (num >= 0xd800 && num <= 0xdfff)) {
                    num = 0xfffd;
                }

                return String.fromCodePoint(num);
            });
    },

    /**
     * Try to extract metadata from JSON-LD object.
     * For now, only Schema.org objects of type Article or its subtypes are supported.
     * @return Object with any metadata that could be extracted (possibly none)
     */
    _getJSONLD(doc) {
        var scripts = this._getAllNodesWithTag(doc, ["script"]);

        var metadata;

        this._forEachNode(scripts, function (jsonLdElement) {
            if (
                !metadata &&
                jsonLdElement.getAttribute("type") === "application/ld+json"
            ) {
                try {
                    // Strip CDATA markers if present
                    var content = jsonLdElement.textContent.replace(
                        /^\s*<!\[CDATA\[|\]\]>\s*$/g,
                        ""
                    );
                    var parsed = JSON.parse(content);

                    if (Array.isArray(parsed)) {
                        parsed = parsed.find(it => {
                            return (
                                it["@type"] &&
                                it["@type"].match(this.REGEXPS.jsonLdArticleTypes)
                            );
                        });
                        if (!parsed) {
                            return;
                        }
                    }

                    var schemaDotOrgRegex = /^https?\:\/\/schema\.org\/?$/;
                    var matches =
                        (typeof parsed["@context"] === "string" &&
                            parsed["@context"].match(schemaDotOrgRegex)) ||
                        (typeof parsed["@context"] === "object" &&
                            typeof parsed["@context"]["@vocab"] == "string" &&
                            parsed["@context"]["@vocab"].match(schemaDotOrgRegex));

                    if (!matches) {
                        return;
                    }

                    if (!parsed["@type"] && Array.isArray(parsed["@graph"])) {
                        parsed = parsed["@graph"].find(it => {
                            return (it["@type"] || "").match(this.REGEXPS.jsonLdArticleTypes);
                        });
                    }

                    if (
                        !parsed ||
                        !parsed["@type"] ||
                        !parsed["@type"].match(this.REGEXPS.jsonLdArticleTypes)
                    ) {
                        return;
                    }

                    metadata = {};

                    if (
                        typeof parsed.name === "string" &&
                        typeof parsed.headline === "string" &&
                        parsed.name !== parsed.headline
                    ) {
                        // we have both name and headline element in the JSON-LD. They should both be the same but some websites like aktualne.cz
                        // put their own name into "name" and the article title to "headline" which confuses Readability. So we try to check if either
                        // "name" or "headline" closely matches the html title, and if so, use that one. If not, then we use "name" by default.

                        var title = this._getArticleTitle();
                        var nameMatches = this._textSimilarity(parsed.name, title) > 0.75;
                        var headlineMatches =
                            this._textSimilarity(parsed.headline, title) > 0.75;

                        if (headlineMatches && !nameMatches) {
                            metadata.title = parsed.headline;
                        } else {
                            metadata.title = parsed.name;
                        }
                    } else if (typeof parsed.name === "string") {
                        metadata.title = parsed.name.trim();
                    } else if (typeof parsed.headline === "string") {
                        metadata.title = parsed.headline.trim();
                    }
                    if (parsed.author) {
                        if (typeof parsed.author.name === "string") {
                            metadata.byline = parsed.author.name.trim();
                        } else if (
                            Array.isArray(parsed.author) &&
                            parsed.author[0] &&
                            typeof parsed.author[0].name === "string"
                        ) {
                            metadata.byline = parsed.author
                                .filter(function (author) {
                                    return author && typeof author.name === "string";
                                })
                                .map(function (author) {
                                    return author.name.trim();
                                })
                                .join(", ");
                        }
                    }
                    if (typeof parsed.description === "string") {
                        metadata.excerpt = parsed.description.trim();
                    }
                    if (parsed.publisher && typeof parsed.publisher.name === "string") {
                        metadata.siteName = parsed.publisher.name.trim();
                    }
                    if (typeof parsed.datePublished === "string") {
                        metadata.datePublished = parsed.datePublished.trim();
                    }
                } catch (err) {
                    this.log(err.message);
                }
            }
        });
        return metadata ? metadata : {};
    },

    /**
     * Attempts to get excerpt and byline metadata for the article.
     *
     * @param {Object} jsonld — object containing any metadata that
     * could be extracted from JSON-LD object.
     *
     * @return Object with optional "excerpt" and "byline" properties
     */
    _getArticleMetadata(jsonld) {
        var metadata = {};
        var values = {};
        var metaElements = this._doc.getElementsByTagName("meta");

        // property is a space-separated list of values
        var propertyPattern =
            /\s*(article|dc|dcterm|og|twitter)\s*:\s*(author|creator|description|published_time|title|site_name)\s*/gi;

        // name is a single value
        var namePattern =
            /^\s*(?:(dc|dcterm|og|twitter|parsely|weibo:(article|webpage))\s*[-\.:]\s*)?(author|creator|pub-date|description|title|site_name)\s*$/i;

        // Find description tags.
        this._forEachNode(metaElements, function (element) {
            var elementName = element.getAttribute("name");
            var elementProperty = element.getAttribute("property");
            var content = element.getAttribute("content");
            if (!content) {
                return;
            }
            var matches = null;
            var name = null;

            if (elementProperty) {
                matches = elementProperty.match(propertyPattern);
                if (matches) {
                    // Convert to lowercase, and remove any whitespace
                    // so we can match below.
                    name = matches[0].toLowerCase().replace(/\s/g, "");
                    // multiple authors
                    values[name] = content.trim();
                }
            }
            if (!matches && elementName && namePattern.test(elementName)) {
                name = elementName;
                if (content) {
                    // Convert to lowercase, remove any whitespace, and convert dots
                    // to colons so we can match below.
                    name = name.toLowerCase().replace(/\s/g, "").replace(/\./g, ":");
                    values[name] = content.trim();
                }
            }
        });

        // get title
        metadata.title =
            jsonld.title ||
            values["dc:title"] ||
            values["dcterm:title"] ||
            values["og:title"] ||
            values["weibo:article:title"] ||
            values["weibo:webpage:title"] ||
            values.title ||
            values["twitter:title"] ||
            values["parsely-title"];

        if (!metadata.title) {
            metadata.title = this._getArticleTitle();
        }

        const articleAuthor =
            typeof values["article:author"] === "string" &&
            !this._isUrl(values["article:author"])
                ? values["article:author"]
                : undefined;

        // get author
        metadata.byline =
            jsonld.byline ||
            values["dc:creator"] ||
            values["dcterm:creator"] ||
            values.author ||
            values["parsely-author"] ||
            articleAuthor;

        // get description
        metadata.excerpt =
            jsonld.excerpt ||
            values["dc:description"] ||
            values["dcterm:description"] ||
            values["og:description"] ||
            values["weibo:article:description"] ||
            values["weibo:webpage:description"] ||
            values.description ||
            values["twitter:description"];

        // get site name
        metadata.siteName = jsonld.siteName || values["og:site_name"];

        // get article published time
        metadata.publishedTime =
            jsonld.datePublished ||
            values["article:published_time"] ||
            values["parsely-pub-date"] ||
            null;

        // in many sites the meta value is escaped with HTML entities,
        // so here we need to unescape it
        metadata.title = this._unescapeHtmlEntities(metadata.title);
        metadata.byline = this._unescapeHtmlEntities(metadata.byline);
        metadata.excerpt = this._unescapeHtmlEntities(metadata.excerpt);
        metadata.siteName = this._unescapeHtmlEntities(metadata.siteName);
        metadata.publishedTime = this._unescapeHtmlEntities(metadata.publishedTime);

        return metadata;
    },

    /**
     * Check if node is image, or if node contains exactly only one image
     * whether as a direct child or as its descendants.
     *
     * @param Element
     **/
    _isSingleImage(node) {
        while (node) {
            if (node.tagName === "IMG") {
                return true;
            }
            if (node.children.length !== 1 || node.textContent.trim() !== "") {
                return false;
            }
            node = node.children[0];
        }
        return false;
    },

    /**
     * Find all <noscript> that are located after <img> nodes, and which contain only one
     * <img> element. Replace the first image with the image from inside the <noscript> tag,
     * and remove the <noscript> tag. This improves the quality of the images we use on
     * some sites (e.g. Medium).
     *
     * @param Element
     **/
    _unwrapNoscriptImages(doc) {
        // Find img without source or attributes that might contains image, and remove it.
        // This is done to prevent a placeholder img is replaced by img from noscript in next step.
        var imgs = Array.from(doc.getElementsByTagName("img"));
        this._forEachNode(imgs, function (img) {
            for (var i = 0; i < img.attributes.length; i++) {
                var attr = img.attributes[i];
                switch (attr.name) {
                    case "src":
                    case "srcset":
                    case "data-src":
                    case "data-srcset":
                        return;
                }

                if (/\.(jpg|jpeg|png|webp)/i.test(attr.value)) {
                    return;
                }
            }

            img.remove();
        });

        // Next find noscript and try to extract its image
        var noscripts = Array.from(doc.getElementsByTagName("noscript"));
        this._forEachNode(noscripts, function (noscript) {
            // Parse content of noscript and make sure it only contains image
            if (!this._isSingleImage(noscript)) {
                return;
            }
            var tmp = doc.createElement("div");
            // We're running in the document context, and using unmodified
            // document contents, so doing this should be safe.
            // (Also we heavily discourage people from allowing script to
            // run at all in this document...)
            // eslint-disable-next-line no-unsanitized/property
            tmp.innerHTML = noscript.innerHTML;

            // If noscript has previous sibling and it only contains image,
            // replace it with noscript content. However we also keep old
            // attributes that might contains image.
            var prevElement = noscript.previousElementSibling;
            if (prevElement && this._isSingleImage(prevElement)) {
                var prevImg = prevElement;
                if (prevImg.tagName !== "IMG") {
                    prevImg = prevElement.getElementsByTagName("img")[0];
                }

                var newImg = tmp.getElementsByTagName("img")[0];
                for (var i = 0; i < prevImg.attributes.length; i++) {
                    var attr = prevImg.attributes[i];
                    if (attr.value === "") {
                        continue;
                    }

                    if (
                        attr.name === "src" ||
                        attr.name === "srcset" ||
                        /\.(jpg|jpeg|png|webp)/i.test(attr.value)
                    ) {
                        if (newImg.getAttribute(attr.name) === attr.value) {
                            continue;
                        }

                        var attrName = attr.name;
                        if (newImg.hasAttribute(attrName)) {
                            attrName = "data-old-" + attrName;
                        }

                        newImg.setAttribute(attrName, attr.value);
                    }
                }

                noscript.parentNode.replaceChild(tmp.firstElementChild, prevElement);
            }
        });
    },

    /**
     * Removes script tags from the document.
     *
     * @param Element
     **/
    _removeScripts(doc) {
        this._removeNodes(this._getAllNodesWithTag(doc, ["script", "noscript"]));
    },

    /**
     * Check if this node has only whitespace and a single element with given tag
     * Returns false if the DIV node contains non-empty text nodes
     * or if it contains no element with given tag or more than 1 element.
     *
     * @param Element
     * @param string tag of child element
     **/
    _hasSingleTagInsideElement(element, tag) {
        // There should be exactly 1 element child with given tag
        if (element.children.length != 1 || element.children[0].tagName !== tag) {
            return false;
        }

        // And there should be no text nodes with real content
        return !this._someNode(element.childNodes, function (node) {
            return (
                node.nodeType === this.TEXT_NODE &&
                this.REGEXPS.hasContent.test(node.textContent)
            );
        });
    },

    _isElementWithoutContent(node) {
        return (
            node.nodeType === this.ELEMENT_NODE &&
            !node.textContent.trim().length &&
            (!node.children.length ||
                node.children.length ==
                node.getElementsByTagName("br").length +
                node.getElementsByTagName("hr").length)
        );
    },

    /**
     * Determine whether element has any children block level elements.
     *
     * @param Element
     */
    _hasChildBlockElement(element) {
        return this._someNode(element.childNodes, function (node) {
            return (
                this.DIV_TO_P_ELEMS.has(node.tagName) ||
                this._hasChildBlockElement(node)
            );
        });
    },

    /***
     * Determine if a node qualifies as phrasing content.
     * https://developer.mozilla.org/en-US/docs/Web/Guide/HTML/Content_categories#Phrasing_content
     **/
    _isPhrasingContent(node) {
        return (
            node.nodeType === this.TEXT_NODE ||
            this.PHRASING_ELEMS.includes(node.tagName) ||
            ((node.tagName === "A" ||
                    node.tagName === "DEL" ||
                    node.tagName === "INS") &&
                this._everyNode(node.childNodes, this._isPhrasingContent))
        );
    },

    _isWhitespace(node) {
        return (
            (node.nodeType === this.TEXT_NODE &&
                node.textContent.trim().length === 0) ||
            (node.nodeType === this.ELEMENT_NODE && node.tagName === "BR")
        );
    },

    /**
     * Get the inner text of a node - cross browser compatibly.
     * This also strips out any excess whitespace to be found.
     *
     * @param Element
     * @param Boolean normalizeSpaces (default: true)
     * @return string
     **/
    _getInnerText(e, normalizeSpaces) {
        normalizeSpaces =
            typeof normalizeSpaces === "undefined" ? true : normalizeSpaces;
        var textContent = e.textContent.trim();

        if (normalizeSpaces) {
            return textContent.replace(this.REGEXPS.normalize, " ");
        }
        return textContent;
    },

    /**
     * Get the number of times a string s appears in the node e.
     *
     * @param Element
     * @param string - what to split on. Default is ","
     * @return number (integer)
     **/
    _getCharCount(e, s) {
        s = s || ",";
        return this._getInnerText(e).split(s).length - 1;
    },

    /**
     * Remove the style attribute on every e and under.
     * TODO: Test if getElementsByTagName(*) is faster.
     *
     * @param Element
     * @return void
     **/
    _cleanStyles(e) {
        if (!e || e.tagName.toLowerCase() === "svg") {
            return;
        }

        // Remove `style` and deprecated presentational attributes
        for (var i = 0; i < this.PRESENTATIONAL_ATTRIBUTES.length; i++) {
            e.removeAttribute(this.PRESENTATIONAL_ATTRIBUTES[i]);
        }

        if (this.DEPRECATED_SIZE_ATTRIBUTE_ELEMS.includes(e.tagName)) {
            e.removeAttribute("width");
            e.removeAttribute("height");
        }

        var cur = e.firstElementChild;
        while (cur !== null) {
            this._cleanStyles(cur);
            cur = cur.nextElementSibling;
        }
    },

    /**
     * Get the density of links as a percentage of the content
     * This is the amount of text that is inside a link divided by the total text in the node.
     *
     * @param Element
     * @return number (float)
     **/
    _getLinkDensity(element) {
        var textLength = this._getInnerText(element).length;
        if (textLength === 0) {
            return 0;
        }

        var linkLength = 0;

        // XXX implement _reduceNodeList?
        this._forEachNode(element.getElementsByTagName("a"), function (linkNode) {
            var href = linkNode.getAttribute("href");
            var coefficient = href && this.REGEXPS.hashUrl.test(href) ? 0.3 : 1;
            linkLength += this._getInnerText(linkNode).length * coefficient;
        });

        return linkLength / textLength;
    },

    /**
     * Get an elements class/id weight. Uses regular expressions to tell if this
     * element looks good or bad.
     *
     * @param Element
     * @return number (Integer)
     **/
    _getClassWeight(e) {
        if (!this._flagIsActive(this.FLAG_WEIGHT_CLASSES)) {
            return 0;
        }

        var weight = 0;

        // Look for a special classname
        if (typeof e.className === "string" && e.className !== "") {
            if (this.REGEXPS.negative.test(e.className)) {
                weight -= 25;
            }

            if (this.REGEXPS.positive.test(e.className)) {
                weight += 25;
            }
        }

        // Look for a special ID
        if (typeof e.id === "string" && e.id !== "") {
            if (this.REGEXPS.negative.test(e.id)) {
                weight -= 25;
            }

            if (this.REGEXPS.positive.test(e.id)) {
                weight += 25;
            }
        }

        return weight;
    },

    /**
     * Clean a node of all elements of type "tag".
     * (Unless it's a youtube/vimeo video. People love movies.)
     *
     * @param Element
     * @param string tag to clean
     * @return void
     **/
    _clean(e, tag) {
        var isEmbed = ["object", "embed", "iframe"].includes(tag);

        this._removeNodes(this._getAllNodesWithTag(e, [tag]), function (element) {
            // Allow youtube and vimeo videos through as people usually want to see those.
            if (isEmbed) {
                // First, check the elements attributes to see if any of them contain youtube or vimeo
                for (var i = 0; i < element.attributes.length; i++) {
                    if (this._allowedVideoRegex.test(element.attributes[i].value)) {
                        return false;
                    }
                }

                // For embed with <object> tag, check inner HTML as well.
                if (
                    element.tagName === "object" &&
                    this._allowedVideoRegex.test(element.innerHTML)
                ) {
                    return false;
                }
            }

            return true;
        });
    },

    /**
     * Check if a given node has one of its ancestor tag name matching the
     * provided one.
     * @param  HTMLElement node
     * @param  String      tagName
     * @param  Number      maxDepth
     * @param  Function    filterFn a filter to invoke to determine whether this node 'counts'
     * @return Boolean
     */
    _hasAncestorTag(node, tagName, maxDepth, filterFn) {
        maxDepth = maxDepth || 3;
        tagName = tagName.toUpperCase();
        var depth = 0;
        while (node.parentNode) {
            if (maxDepth > 0 && depth > maxDepth) {
                return false;
            }
            if (
                node.parentNode.tagName === tagName &&
                (!filterFn || filterFn(node.parentNode))
            ) {
                return true;
            }
            node = node.parentNode;
            depth++;
        }
        return false;
    },

    /**
     * Return an object indicating how many rows and columns this table has.
     */
    _getRowAndColumnCount(table) {
        var rows = 0;
        var columns = 0;
        var trs = table.getElementsByTagName("tr");
        for (var i = 0; i < trs.length; i++) {
            var rowspan = trs[i].getAttribute("rowspan") || 0;
            if (rowspan) {
                rowspan = parseInt(rowspan, 10);
            }
            rows += rowspan || 1;

            // Now look for column-related info
            var columnsInThisRow = 0;
            var cells = trs[i].getElementsByTagName("td");
            for (var j = 0; j < cells.length; j++) {
                var colspan = cells[j].getAttribute("colspan") || 0;
                if (colspan) {
                    colspan = parseInt(colspan, 10);
                }
                columnsInThisRow += colspan || 1;
            }
            columns = Math.max(columns, columnsInThisRow);
        }
        return { rows, columns };
    },

    /**
     * Look for 'data' (as opposed to 'layout') tables, for which we use
     * similar checks as
     * https://searchfox.org/mozilla-central/rev/f82d5c549f046cb64ce5602bfd894b7ae807c8f8/accessible/generic/TableAccessible.cpp#19
     */
    _markDataTables(root) {
        var tables = root.getElementsByTagName("table");
        for (var i = 0; i < tables.length; i++) {
            var table = tables[i];
            var role = table.getAttribute("role");
            if (role == "presentation") {
                table._readabilityDataTable = false;
                continue;
            }
            var datatable = table.getAttribute("datatable");
            if (datatable == "0") {
                table._readabilityDataTable = false;
                continue;
            }
            var summary = table.getAttribute("summary");
            if (summary) {
                table._readabilityDataTable = true;
                continue;
            }

            var caption = table.getElementsByTagName("caption")[0];
            if (caption && caption.childNodes.length) {
                table._readabilityDataTable = true;
                continue;
            }

            // If the table has a descendant with any of these tags, consider a data table:
            var dataTableDescendants = ["col", "colgroup", "tfoot", "thead", "th"];
            var descendantExists = function (tag) {
                return !!table.getElementsByTagName(tag)[0];
            };
            if (dataTableDescendants.some(descendantExists)) {
                this.log("Data table because found data-y descendant");
                table._readabilityDataTable = true;
                continue;
            }

            // Nested tables indicate a layout table:
            if (table.getElementsByTagName("table")[0]) {
                table._readabilityDataTable = false;
                continue;
            }

            var sizeInfo = this._getRowAndColumnCount(table);

            if (sizeInfo.columns == 1 || sizeInfo.rows == 1) {
                // single column/row tables are commonly used for page layout purposes.
                table._readabilityDataTable = false;
                continue;
            }

            if (sizeInfo.rows >= 10 || sizeInfo.columns > 4) {
                table._readabilityDataTable = true;
                continue;
            }
            // Now just go by size entirely:
            table._readabilityDataTable = sizeInfo.rows * sizeInfo.columns > 10;
        }
    },

    /* convert images and figures that have properties like data-src into images that can be loaded without JS */
    _fixLazyImages(root) {
        this._forEachNode(
            this._getAllNodesWithTag(root, ["img", "picture", "figure"]),
            function (elem) {
                // In some sites (e.g. Kotaku), they put 1px square image as base64 data uri in the src attribute.
                // So, here we check if the data uri is too short, just might as well remove it.
                if (elem.src && this.REGEXPS.b64DataUrl.test(elem.src)) {
                    // Make sure it's not SVG, because SVG can have a meaningful image in under 133 bytes.
                    var parts = this.REGEXPS.b64DataUrl.exec(elem.src);
                    if (parts[1] === "image/svg+xml") {
                        return;
                    }

                    // Make sure this element has other attributes which contains image.
                    // If it doesn't, then this src is important and shouldn't be removed.
                    var srcCouldBeRemoved = false;
                    for (var i = 0; i < elem.attributes.length; i++) {
                        var attr = elem.attributes[i];
                        if (attr.name === "src") {
                            continue;
                        }

                        if (/\.(jpg|jpeg|png|webp)/i.test(attr.value)) {
                            srcCouldBeRemoved = true;
                            break;
                        }
                    }

                    // Here we assume if image is less than 100 bytes (or 133 after encoded to base64)
                    // it will be too small, therefore it might be placeholder image.
                    if (srcCouldBeRemoved) {
                        var b64starts = parts[0].length;
                        var b64length = elem.src.length - b64starts;
                        if (b64length < 133) {
                            elem.removeAttribute("src");
                        }
                    }
                }

                // also check for "null" to work around https://github.com/jsdom/jsdom/issues/2580
                if (
                    (elem.src || (elem.srcset && elem.srcset != "null")) &&
                    !elem.className.toLowerCase().includes("lazy")
                ) {
                    return;
                }

                for (var j = 0; j < elem.attributes.length; j++) {
                    attr = elem.attributes[j];
                    if (
                        attr.name === "src" ||
                        attr.name === "srcset" ||
                        attr.name === "alt"
                    ) {
                        continue;
                    }
                    var copyTo = null;
                    if (/\.(jpg|jpeg|png|webp)\s+\d/.test(attr.value)) {
                        copyTo = "srcset";
                    } else if (/^\s*\S+\.(jpg|jpeg|png|webp)\S*\s*$/.test(attr.value)) {
                        copyTo = "src";
                    }
                    if (copyTo) {
                        //if this is an img or picture, set the attribute directly
                        if (elem.tagName === "IMG" || elem.tagName === "PICTURE") {
                            elem.setAttribute(copyTo, attr.value);
                        } else if (
                            elem.tagName === "FIGURE" &&
                            !this._getAllNodesWithTag(elem, ["img", "picture"]).length
                        ) {
                            //if the item is a <figure> that does not contain an image or picture, create one and place it inside the figure
                            //see the nytimes-3 testcase for an example
                            var img = this._doc.createElement("img");
                            img.setAttribute(copyTo, attr.value);
                            elem.appendChild(img);
                        }
                    }
                }
            }
        );
    },

    _getTextDensity(e, tags) {
        var textLength = this._getInnerText(e, true).length;
        if (textLength === 0) {
            return 0;
        }
        var childrenLength = 0;
        var children = this._getAllNodesWithTag(e, tags);
        this._forEachNode(
            children,
            child => (childrenLength += this._getInnerText(child, true).length)
        );
        return childrenLength / textLength;
    },

    /**
     * Clean an element of all tags of type "tag" if they look fishy.
     * "Fishy" is an algorithm based on content length, classnames, link density, number of images & embeds, etc.
     *
     * @return void
     **/
    _cleanConditionally(e, tag) {
        if (!this._flagIsActive(this.FLAG_CLEAN_CONDITIONALLY)) {
            return;
        }

        // Gather counts for other typical elements embedded within.
        // Traverse backwards so we can remove nodes at the same time
        // without effecting the traversal.
        //
        // TODO: Consider taking into account original contentScore here.
        this._removeNodes(this._getAllNodesWithTag(e, [tag]), function (node) {
            // First check if this node IS data table, in which case don't remove it.
            var isDataTable = function (t) {
                return t._readabilityDataTable;
            };

            var isList = tag === "ul" || tag === "ol";
            if (!isList) {
                var listLength = 0;
                var listNodes = this._getAllNodesWithTag(node, ["ul", "ol"]);
                this._forEachNode(
                    listNodes,
                    list => (listLength += this._getInnerText(list).length)
                );
                isList = listLength / this._getInnerText(node).length > 0.9;
            }

            if (tag === "table" && isDataTable(node)) {
                return false;
            }

            // Next check if we're inside a data table, in which case don't remove it as well.
            if (this._hasAncestorTag(node, "table", -1, isDataTable)) {
                return false;
            }

            if (this._hasAncestorTag(node, "code")) {
                return false;
            }

            // keep element if it has a data tables
            if (
                [...node.getElementsByTagName("table")].some(
                    tbl => tbl._readabilityDataTable
                )
            ) {
                return false;
            }

            var weight = this._getClassWeight(node);

            this.log("Cleaning Conditionally", node);

            var contentScore = 0;

            if (weight + contentScore < 0) {
                return true;
            }

            if (this._getCharCount(node, ",") < 10) {
                // If there are not very many commas, and the number of
                // non-paragraph elements is more than paragraphs or other
                // ominous signs, remove the element.
                var p = node.getElementsByTagName("p").length;
                var img = node.getElementsByTagName("img").length;
                var li = node.getElementsByTagName("li").length - 100;
                var input = node.getElementsByTagName("input").length;
                var headingDensity = this._getTextDensity(node, [
                    "h1",
                    "h2",
                    "h3",
                    "h4",
                    "h5",
                    "h6",
                ]);

                var embedCount = 0;
                var embeds = this._getAllNodesWithTag(node, [
                    "object",
                    "embed",
                    "iframe",
                ]);

                for (var i = 0; i < embeds.length; i++) {
                    // If this embed has attribute that matches video regex, don't delete it.
                    for (var j = 0; j < embeds[i].attributes.length; j++) {
                        if (this._allowedVideoRegex.test(embeds[i].attributes[j].value)) {
                            return false;
                        }
                    }

                    // For embed with <object> tag, check inner HTML as well.
                    if (
                        embeds[i].tagName === "object" &&
                        this._allowedVideoRegex.test(embeds[i].innerHTML)
                    ) {
                        return false;
                    }

                    embedCount++;
                }

                var innerText = this._getInnerText(node);

                // toss any node whose inner text contains nothing but suspicious words
                if (
                    this.REGEXPS.adWords.test(innerText) ||
                    this.REGEXPS.loadingWords.test(innerText)
                ) {
                    return true;
                }

                var contentLength = innerText.length;
                var linkDensity = this._getLinkDensity(node);
                var textishTags = ["SPAN", "LI", "TD"].concat(
                    Array.from(this.DIV_TO_P_ELEMS)
                );
                var textDensity = this._getTextDensity(node, textishTags);
                var isFigureChild = this._hasAncestorTag(node, "figure");

                // apply shadiness checks, then check for exceptions
                const shouldRemoveNode = () => {
                    const errs = [];
                    if (!isFigureChild && img > 1 && p / img < 0.5) {
                        errs.push(`Bad p to img ratio (img=${img}, p=${p})`);
                    }
                    if (!isList && li > p) {
                        errs.push(`Too many li's outside of a list. (li=${li} > p=${p})`);
                    }
                    if (input > Math.floor(p / 3)) {
                        errs.push(`Too many inputs per p. (input=${input}, p=${p})`);
                    }
                    if (
                        !isList &&
                        !isFigureChild &&
                        headingDensity < 0.9 &&
                        contentLength < 25 &&
                        (img === 0 || img > 2) &&
                        linkDensity > 0
                    ) {
                        errs.push(
                            `Suspiciously short. (headingDensity=${headingDensity}, img=${img}, linkDensity=${linkDensity})`
                        );
                    }
                    if (
                        !isList &&
                        weight < 25 &&
                        linkDensity > 0.2 + this._linkDensityModifier
                    ) {
                        errs.push(
                            `Low weight and a little linky. (linkDensity=${linkDensity})`
                        );
                    }
                    if (weight >= 25 && linkDensity > 0.5 + this._linkDensityModifier) {
                        errs.push(
                            `High weight and mostly links. (linkDensity=${linkDensity})`
                        );
                    }
                    if ((embedCount === 1 && contentLength < 75) || embedCount > 1) {
                        errs.push(
                            `Suspicious embed. (embedCount=${embedCount}, contentLength=${contentLength})`
                        );
                    }
                    if (img === 0 && textDensity === 0) {
                        errs.push(
                            `No useful content. (img=${img}, textDensity=${textDensity})`
                        );
                    }

                    if (errs.length) {
                        this.log("Checks failed", errs);
                        return true;
                    }

                    return false;
                };

                var haveToRemove = shouldRemoveNode();

                // Allow simple lists of images to remain in pages
                if (isList && haveToRemove) {
                    for (var x = 0; x < node.children.length; x++) {
                        let child = node.children[x];
                        // Don't filter in lists with li's that contain more than one child
                        if (child.children.length > 1) {
                            return haveToRemove;
                        }
                    }
                    let li_count = node.getElementsByTagName("li").length;
                    // Only allow the list to remain if every li contains an image
                    if (img == li_count) {
                        return false;
                    }
                }
                return haveToRemove;
            }
            return false;
        });
    },

    /**
     * Clean out elements that match the specified conditions
     *
     * @param Element
     * @param Function determines whether a node should be removed
     * @return void
     **/
    _cleanMatchedNodes(e, filter) {
        var endOfSearchMarkerNode = this._getNextNode(e, true);
        var next = this._getNextNode(e);
        while (next && next != endOfSearchMarkerNode) {
            if (filter.call(this, next, next.className + " " + next.id)) {
                next = this._removeAndGetNext(next);
            } else {
                next = this._getNextNode(next);
            }
        }
    },

    /**
     * Clean out spurious headers from an Element.
     *
     * @param Element
     * @return void
     **/
    _cleanHeaders(e) {
        let headingNodes = this._getAllNodesWithTag(e, ["h1", "h2"]);
        this._removeNodes(headingNodes, function (node) {
            let shouldRemove = this._getClassWeight(node) < 0;
            if (shouldRemove) {
                this.log("Removing header with low class weight:", node);
            }
            return shouldRemove;
        });
    },

    /**
     * Check if this node is an H1 or H2 element whose content is mostly
     * the same as the article title.
     *
     * @param Element  the node to check.
     * @return boolean indicating whether this is a title-like header.
     */
    _headerDuplicatesTitle(node) {
        if (node.tagName != "H1" && node.tagName != "H2") {
            return false;
        }
        var heading = this._getInnerText(node, false);
        this.log("Evaluating similarity of header:", heading, this._articleTitle);
        return this._textSimilarity(this._articleTitle, heading) > 0.75;
    },

    _flagIsActive(flag) {
        return (this._flags & flag) > 0;
    },

    _removeFlag(flag) {
        this._flags = this._flags & ~flag;
    },

    _isProbablyVisible(node) {
        // Have to null-check node.style and node.className.includes to deal with SVG and MathML nodes.
        return (
            (!node.style || node.style.display != "none") &&
            (!node.style || node.style.visibility != "hidden") &&
            !node.hasAttribute("hidden") &&
            //check for "fallback-image" so that wikimedia math images are displayed
            (!node.hasAttribute("aria-hidden") ||
                node.getAttribute("aria-hidden") != "true" ||
                (node.className &&
                    node.className.includes &&
                    node.className.includes("fallback-image")))
        );
    },

    /**
     * Runs readability.
     *
     * Workflow:
     *  1. Prep the document by removing script tags, css, etc.
     *  2. Build readability's DOM tree.
     *  3. Grab the article content from the current dom tree.
     *  4. Replace the current DOM tree with the new one.
     *  5. Read peacefully.
     *
     * @return void
     **/
    parse() {
        // Avoid parsing too large documents, as per configuration option
        if (this._maxElemsToParse > 0) {
            var numTags = this._doc.getElementsByTagName("*").length;
            if (numTags > this._maxElemsToParse) {
                throw new Error(
                    "Aborting parsing document; " + numTags + " elements found"
                );
            }
        }

        // Unwrap image from noscript
        this._unwrapNoscriptImages(this._doc);

        // Extract JSON-LD metadata before removing scripts
        var jsonLd = this._disableJSONLD ? {} : this._getJSONLD(this._doc);

        // Remove script tags from the document.
        this._removeScripts(this._doc);

        this._prepDocument();

        var metadata = this._getArticleMetadata(jsonLd);
        this._metadata = metadata;
        this._articleTitle = metadata.title;

        var articleContent = this._grabArticle();
        if (!articleContent) {
            return null;
        }

        this.log("Grabbed: " + articleContent.innerHTML);

        this._postProcessContent(articleContent);

        // If we haven't found an excerpt in the article's metadata, use the article's
        // first paragraph as the excerpt. This is used for displaying a preview of
        // the article's content.
        if (!metadata.excerpt) {
            var paragraphs = articleContent.getElementsByTagName("p");
            if (paragraphs.length) {
                metadata.excerpt = paragraphs[0].textContent.trim();
            }
        }

        var textContent = articleContent.textContent;
        return {
            title: this._articleTitle,
            byline: metadata.byline || this._articleByline,
            dir: this._articleDir,
            lang: this._articleLang,
            content: this._serializer(articleContent),
            textContent,
            length: textContent.length,
            excerpt: metadata.excerpt,
            siteName: metadata.siteName || this._articleSiteName,
            publishedTime: metadata.publishedTime,
        };
    },
};

if (typeof module === "object") {
    /* eslint-disable-next-line no-redeclare */
    /* global module */
    module.exports = Readability;
}
